A global navigation satellite system (GNSS) includes constellations of earth orbiting satellites that constantly transmit orbit information and ranging signals. The dominant GNSS has been the Global Positioning System (GPS) but competing systems such as Glonass, Galileo, Compass, and QZSS exist or are in development. Orbit information and ranging signals transmitted by GNSS satellites are received by GNSS receivers. To determine its position, a GNSS receiver acquires and tracks satellite signals from three or more satellites so as to measure a range from itself to each satellite and also to demodulate the transmitted orbit information. Recently, with the availability of multiple GNSS's, it is desirable to improve the receiver position accuracy and satellite availability of GPS receivers by adding the capability for GPS receivers to receive signals from other GNSS's, such as Glonass. However, adding the capability to receive Glonass signals in GPS receivers increases the power consumption of the receivers. This presents particular challenges for receivers with stringent power constraints, especially in view of the tight power budget imposed by the increasing integration of GPS receivers into handheld devices and other battery-powered applications. Existing techniques for power reduction include minimizing the on-time period of a GNSS receiver and maintaining a more accurate real time clock or a more accurate temperature-compensated crystal oscillator (TCXO) to allow more rapid acquisition of satellite signals when the receiver enters the on-time period. However, these techniques tend to reduce power consumption without maintaining an acceptable position fixing accuracy. Other techniques such as running a receiver at a periodic duty cycle may not maintain sufficient signal tracking to yield significant power savings when the receiver upon wakeup has to expend energy for the tracking loops to pull in satellite signals that are no longer in track. Therefore, it is desirable to find a more flexible technique to reduce power consumption in GNSS receivers while allowing the receivers to take advantage of the increased availability of satellite signals from multiple GNSS's to maintain a minimum performance metric.